Such semiconductor components are used in “half-bridges” in drive technology, for example. A half-bridge of this type typically comprises two semiconductor switches with a respective load path and a respective control connection. In this case, the load paths of the two semiconductor switches are connected in series, and applying a control voltage to one of the control connections controls the current flowing via the load path of the associated semiconductor switch. The power switch connected to the lower potential of the supply voltage, preferably to ground, is usually referred to as a low-side switch in this case, and the other is accordingly referred to as a high-side switch.
Normally, the supply voltage which is present across such a half-bridge through the series connection of the load paths is several hundred volts.
The normally high supply voltages mean that the voltages which are required for actuation and which are present across the control connections of the semiconductor switches are also significantly different, typically by several hundred volts.
Usually, the control connections of the two semiconductor switches are actuated by means of actuation electronics which output ground-referenced signals which need to be converted to a high potential in order to actuate the high-side switch.
So that it is not necessary to design such control electronics to be resistant to high voltage, it is expedient to isolate the potentials of the control electronics and of at least one of the control connections.
One option for isolating potentials is indicated in the article by Kaschani, K. T. et al.: “Coreless transformer a new technology for half bridge driver IC's”, PCIM 2003, Nuremburg. In this case, the potentials are isolated by means of a transformer which comprises two inductively coupled windings and which is arranged on a semiconductor body.
One option for implementing an arrangement of this type is shown in FIG. 1. In this case, a number of patterned metallization planes 10, 20, 30, 40 are arranged above a semiconductor body 9 and have insulating layers arranged between them.
A first winding 71 and a second winding 72 in a transformer 71, 72 are in the form of planar, spiraled windings 71, 72 and are arranged opposite one another in two different metallization planes 10 and 20. Preferably, both windings have the same center point and also the same external diameter, so as to ensure the best possible magnetic coupling. During operation, a large potential difference can develop between the two windings and can result in very high electrical fields which can adversely affect their environment, particularly surrounding circuit parts.
To avoid these unwanted effects, the transformer has a protective ring 1, 2 arranged around it which is normally electrically conductively connected to the semiconductor body 9.
The protective ring 1, 2 comprises an electrically conductive structure which is formed from metal portions 1a-1d and from vertical connecting elements 2a-2c, such as contact holes. The metal portions 1a-1d are respectively arranged in one of the metallization planes 10, 20, 30, 40 and are at the same lateral spacing from the first planar winding 71. Connecting elements 2a-2c which penetrate the insulating layers connect the metal portions 1a-1d to one another in electrically conductive fashion in the vertical direction of the semiconductor body 9. The protective ring arrangement is connected to the semiconductor body 9 by means of a connection contact 2d. 
To protect the exterior of the component from chemical and mechanical influences, the top metallization plane 10 has a passivation layer 6 applied to it which may comprise a layer or a plurality of layer elements. The normally high potential difference between the first planar winding 71 and the protective ring 1, 2 means that the passivation layer 6 may be damaged.